Electronic control circuit for automatically fed machines

ABSTRACT

There is provided an apparatus controlling an automatically fed machine having multiple feed stations and a conveyance path along which workpieces are fed. A pulse generator operatively connected to the apparatus generates a plurality of timing pulses in timed relationship with feeding of the workpieces, and a multiple of workpiece detection sensors produce signals when detecting workpieces in several of the stations, such signals being stored in associated memory units in time relationship with several of the timing pulses. An output signal from one of the memory units impulses a shift register, which is then stepped for each machine cycle by one of the timing pulses. An output signal from the shift register is adapted to energize a work-performing apparatus should the workpieces be conveyed properly, and another output signal from the shift register is compared in a comparator with an output signal from the other of the memory units. Should the two comparator signals agree in point of time, an output signal from the comparator will energize a machine control that keeps the machine operating. Should the two signals not compare in point of time, both the work performing apparatus and the machine control remain deenergized, and the machine stops.

United States Patent Gross Jan. 18, 1972 [72] Inventor: Clarence R.Gross, Hastings, Mich.

[731 Assignee: Gull & Western Industrial Products Compuny, Grand Rapids,Mich.

[22] Filed: Sept. 25, 1969 [21] APPLNOJ 870,830

Related US. Application Data [62] Division of Ser. No. 698,657, Jan. 17,1968, Pat. No.

[52] US. Cl ..228/8, 228/4, 318/466 [51] Int. Cl. ....B23li 1/00, B231:5/00 [58] Field of Search. ..228/4, 8; I 13/8; 318/466 [56] ReferencesCited UNITED STATES PATENTS 3,527,125 9/1970 Ferrier ..228/8 X 2,773,46512/1956 Gedde ...113/8 2,458,008 1/1949 Kruse ..1l3/8 PrimaryExaminer-John R Campbell Assistant Examiner- Robert J. Craig A rtomey-Meyer, Tilberry and Body ABSTRACT There is provided an apparatuscontrolling an automatically fed machine having multiple feed stationsand a conveyance path along which workpieces are fed. A pulse generatoroperatively connected to the apparatus generates a plurality of timingpulses in timed relationship with feeding of the workpieces, and amultiple of work piece detection sensors produce signals when detectingworkpieces in several of the stations, such signals being stored inassociated memory units in time relationship with several of the timingpulses. An output signal from one of the memory units impulses a shiftregister, which is then stepped for each machine cycle by one of thetiming pulses. An output signal from the shift register is adapted toenergize a work-performing apparatus should the workpieces be conveyedproperly, and another output signal from the shift register is comparedin a comparator with an output signal from the other of the memoryunits. Should the two comparator signals agree in point of time, anoutput signal from the comparator will energize a machine control thatkeeps the machine operating. Should the two signals not compare in pointof time, both the work performing apparatus and the machine controlremain deenergized, and the machine stops.

8 Claims, 7 Drawing Figures MANUAL STAKE R/ CONTROL WELD A CONTROL B c FT IMING WORK I L n /D PULSE ECE AND EM RY SHIFT SENSOR UNIT REG, LINESPOT WELD CONTROL FOURTH I TIMING PULSE FIRST TIMING TIME PULSE DELAY JI M N m /P B D MEMORY COMPARITOR AMR MOTOR SENSOR UNIT CONTROL PATENTEBJANWLJ Z 3,635,390

SHEEI [1F 4 (STEER ON) D (PRIME) H B (STEER OFF) (INHIBIT) 6 2I4 SET 2I4NOT OUTPUT 2IO INVENTOR.

CLARENCE R. GROSS ELECTRONIC CONTROL CIRCUIT FOR AUTOMATICALLY FEDMACHINES This application is a division of US. Pat. Application Ser. No.698,657 filed Jan. 17, l968, and now US. Pat. No. 3,534,897 issued Oct.20, 1970.

This invention relates to control circuits for automatic machines and,more particularly, to circuits for controlling material beingtransported through automatically fed machines when a number ofmalfunctions occur, characterized by misfeeding, jamming or generallyimproper material movement.

The present invention is particularly directed to a control circuit fora can body making machine and will be discussed with particularreference thereto; however. the invention has somewhat broaderapplications and is adaptable for use whenever material beingautomatically fed through a machine is to be controlled.

A number of electronic control circuits for monitoring material movementand controlling automatic fed machines have been directed in the past tosuch as, laundry control, bottle recognition apparatus, and linearmeasurement systems. All of these prior art control circuits have beenlimited to single station, or single item control, and not to control ofautomatic fed machines providing for continuous control of each itembeing fed through multiple work stations within the machine inoperation.

The control circuit of the type herein described is particularlydirected to machines for forming lap welded aluminum can bodies, as isdescribed in patent application "Method And Machine For Forming LapWelded Aluminum Can Bodies," U.S. Ser. No. 573,971, filed on Aug. 22,1966, now abandoned, assigned to the assignee of the present invention,and which is incorporated by reference herein.

Application No. 573,971 is directed to a machine and process for makingcan bodies out of aluminum. It is directed to an ultrasonic weldingprocess to produce can bodies out of aluminum, at a high productionrate, with the can body thickness dependent upon the thickness of theblank used, and with a desirable final appearance. Prior art processesfor making can bodies out of aluminum created can bodies of variablethicknesses, poor welded or soldered joints and discolored appearances.

The apparatus disclosed in U.S. Pat. application, Ser. No. 573,971,forms a generally cylindrical can body from a flat aluminum blank,transporting the material fed from a hopper through several idlestations and to several work stations where the forming and then thewelding is done. The can body is formed with overlapped edges, and thenstake welded and finally line spot welded by an ultrasonic weld processbefore being ejected from the machine. The ultrasonic welders used aretwo frequency converters with controls, having a capacity of 2,000 wattsand 1,000 watts, which are marketed by Sonobond Corporation.

In accordance with the present invention there is provided an apparatusfor controlling an automatically fed machine wherein workpieces aretransported along a conveyance path and a means is responsive to theentrance of each said workpiece into an input station for storing amemory of the entrance, a register means is responsive to thetransportation of each workpiece through the machine for controlling aworkperforming apparatus to perform work on each workpiece in the eventeach workpiece is being transported through the machine, another meansis responsive to the presence of each workpiece at an output station forstoring a memory of the presence thereof, and a comparator means sensesif a difference, in point of time, in the outputs of the register meansand the output responsive means exists, and if such a difference exists,the comparator means stops the machine.

The primary object of this invention is the provision of a controlapparatus for an automatically fed machine.

Another object of this invention is the provision of an electroniccontrol circuit for an automatically fed machine.

Another object of this invention is the provision of a control circuitfor stopping the machine and the welding process if material is notpresent at the welding station of the machine.

Another object of this invention is the provision of a control circuithaving a shift register to indicate where material is within themachine, and a differential comparator to stop the machine and weldingprocess in the event the material has not been fed through the machine.

These and other objects of the invention will become ap parent from thefollowing description of a specific example embodying the invention andthe attached claims when taken in conjunction with the accompanyingdrawings illustrating the described specific example embodying theinvention in which:

FIG. I is a block diagram of the embodiment of the control apparatus ofthe present invention;

FIG. 2 is a diagrammatic representation of the transportation of thematerial through the machine in conjunction with the control apparatus;

FIG. 3 is a partial sectional view taken along line 3-3 of FIG. 2 andlooking in the direction of the arrows of the drive shaft with attachedvanes, illustrative of the timed relationship of the limit switchoperating vanes with the feeding of the material through the machine;

FIG. 4 is a schematic circuit of the block diagram of FIG. I;

FIG. 5 is a schematic of the shift register and manual controls for eachstate of the shift register as shown in FIG. 4;

FIG. 6 is a wiring diagram of each stage of the shifi register, with theappended terminals thereto; and,

FIG. 7 is a cut away view illustrative of the body sensor and pickupmethod used at the line weld station of the embodiment of FIG. I.

GENERAL DESCRIPTION Referring now to the drawings which are for thepurpose of illustrating a preferred embodiment of the invention and notfor the purpose of limiting the same, ablock diagram of the controlapparatus of the present invention is illustrated in FIG.

As illustrated in FIG. I, workpiece sensor A is adaptable for sensingthe feeding of a workpiece into the input station of the machine undercontrol. An output from workpiece sensor A is Anded" with a first timingpulse I in a standard AND circuit B. The output from AND circuit 8,shown as I, is used to control a memory unit C, in the event a workpiecehas been sensed by a workpiece sensor A. Memory unit C has an output,shown as II, which is designed to prime the shift register D.

Shift register D comprises a plurality of bistable flip-flops, eachflip-flop of the design, such, that it will turn on" with a set pulse ifprimed with a prime output from a preceding flip flop, and it will turn"off" with a set pulse if it has not been primed with a prime outputfrom a preceding flip-flop.

The prime output II from memory unit C is designed to prime the firstflip-flop of shift register D, and a second timing pulse 2' is used toturn on any flip-flop that has been primed by the preceding stage or toturn off any flip-flop that has not been primed by the preceding stage.The flip-flops used in shift register D will be explained in greaterdetail subsequently. As is shown in FIG. 1, an output from shiftregister D is amplified in amplifier E so as to produce a control outputIII, the function of which is to control a stake weld control unit G inconjunction with a third timing pulse 3'.

A second sensor, body sensor 1, has an output designed to set a secondmemory unit K some predetermined time later, after a workpiece has beensensed by workpiece sensor A. The correlation between workpiece sensor Aand body sensor J will be explained subsequently. First timing pulse Ialso has the function of resetting memory unit K only in the event thatbody sensor J has not sensed a workpiece at some predetermined pointwithin the machine being controlled. In the event that memory unit K hasbeen set by body sensor J, such memory unit K will produce output VIwhich is taken to a comparator M. A second output from shift register Dis taken through time delay L to produce an output V, which is alsotaken to comparator unit M. The purpose of comparator M is to insurethat both inputs V and VI are present within the machine at the sametime, so as to produce an output signal. This output signal is passedthrough amplifier N to produce output VII, which is taken to a motorcontrol unit P, to keep the apparatus being controlled in the "run"status. Should there be no output VII from amplifier N, motor controlunit P will be deenergized and the apparatus being controlled will bestopped.

The second output from shift register D is also taken through amplifierF to produce an output, shown as IV, which is taken to a line spot weldcontrol unit H. The output from body sensor J is also taken to line spotweld control unit H, where, in conjunction with a fourth timing pulse 4'and output IV, the three inpum to line spot weld control H energize theweld control equipment at line spot control H. Manual control R is usedfor setting or resetting the individual flip-flops that make up shiftregister D, in the event of a power failure, or in the event that theworkpieces being transported through the apparatus under control do notprogress through the machine in the desired sequence.

FIG. 2 is illustrative of an apparatus that can be controlled by thepresent invention. In FIG. 2, vanes I, 2, 3 and 4 coact withvane-operated limit switches I0, which may be standard magneticallyoperated reed switches for the purpose of this invention, to produce thefirst, second, third and fourth timing pulses, 1'4' as shown in FIG. I.Vanes 1 through 4 are shown attached to a drive shaft 12 which is drivenby a motor I4 of the apparatus being controlled. Also attached to shaftI2 is a vertical bevel gear driving a horizontal bevel gear for rotating3 second shaft I8 in timed relationship with shaft I2. Attached torotating shaft 18 is a drive cam 20 with a pivot stud 22 mounted inpivotal arrangement with drive cam 20 and also with one end of a feedbar crank 24. A second pivot stud 26 is attached in pivotal arrangementto the other end of feed bar crank 24 and also with a feed bar 28. Feedbar 28 is reciprocated in an oscillatory manner under the control ofpivot stud 26 and feed bar crank 24. FIG. 2 shows feed bar 28 in itsfull forward movement. The timing relationship between the feed bar 28and drive shaft 12 is such that for each full oscillatory movement offeed bar 28, drive shaft 12 will rotate through one revolution, or 360.Thus, it is seen that the full oscillatory movement of feed bar 28 isequivalent to 360 of machine time.

FIG. 2 is generally illustrative of the reciprocating movement impartedto a feed bar 28 of a welding apparatus. Hopper 30 is shown containingworkpieces 32 which are deposited upon feed bar 28 in a manner wellknown in the welding industry. As workpieces 32 are fed onto feed bar 28from hopper 30 they are held in place by means of transporting devices,generally illustrated by feed fingers 34 and compression springs 36. Thetransporting devices, thus, have been designed to move under theworkpieces as the feed bar 28 is returned to its far left position. Notshown in FIG. 2, are clamping devices which are also well known in thewelding industry, for retaining workpieces 32 in the machine position towhich they have been transported as feed bar 28 returns to its leftmostposition.

The welding apparatus, as illustrated in FIG. 2, may be composed of anynumber of work stations, and not necessarily the number that isillustrated in FIG. 2. However, to best illustrate this invention, sevenwork stations have been shown, the last three stations illustrating howa generally flat workpiece 32 has been formed into a can body 39 arounda horn 38, a process that is well known in the art.

Workpiece sensor 40 is generally illustrative of the workpiece sensor Aas was shown in FIG. I. Workpiece sensor 40 generally senses workpiece32 by means of a photoelectric beam 42 in a station that could beconsidered as an input station. A form and stake weld station 60 isillustrative of the position of a body piece 39 which is about to beoperated upon by stake weld control G as shown in FIG. 1. Line weldstation 80 is illustrative of the position in the apparatus where a bodypiece 39 is about to have work performed upon it by line spot weldcontrol H, as shown in FIG. 1. Body photo scanner I00 is generallyillustrative of the body sensor J of FIG. I. and the photoelectric beamof body scanner is shown as bearn I02. Thus, it is seen that should anyof the workpieces not be transported through the apparatus under controlin the preferred sequence, an output from body photo scanner 100 can beutilized to control motor 14, and an output from workpiece sensor 40 canbe utilized for setting a memory unit, as illustrated by memory unit Cin FIG. I.

FIG. 3 is a partial sectional view along line 3-3 of FIG. 2.illustrating the timed relationship of the vanes which are attached toshaft I2, and therefore rotate at the same speed as shaft 12. FIG. 3illustrates the timing duration that the normally open points of thevane operated limit switches I0 are closed to give the timing pulsesindicated in FIG. I, and also their relationship with one another duringthe machine cycle.

Illustrated in FIG. 4, is a schematic diagram of the control circuitshown in block diagram form in FIG. I, which is operative to control amachine forming lap-welded aluminum can bodies, as disclosed by US.application No. 573,97 l and assigned to the assignee of this invention.

In FIG. 4 the motor 14, feed bar 28, workpiece 32 and body piece 39 areshown as illustrative of the drive mechanism and material movementthrough the apparatus under control. The sensors 40 and I00 in thepreferred embodiment shown, are photoelectric scanners of the type,MEX-5 5-SA lO-AE, with sensor 40 using a transistorized amplifier,MEK-55-AAIOA, and sensor 100 using a transistorized amplifier, MEK-SS-AC IO-A, all units being manufactured and sold by MachineryElectrification, lnc., Northboro, Mass. The indicated scanners are ofthe type usable with I 15 v., 60 cycle AC and which incorporate a relay,with normally open (N/O) points, such that the relay is energizable whenreflected light reaches a photocell within the scanner unit. Anadditional feature of the scanner used for sensor 100 is the built-indelay unit wherein the energized relay will remain energized only for apredetermined time upon the sensing of a reflecting object and then willbecome deenergized, necessitating the movement of the reflecting objectfrom beneath the photo beam before the sensing relay can be energizedagain. Should the reflecting object not move out of the reflecting beam,the sensing relay will not become energized again, thus permittingobject movement sensing out of the particular machine station as well asobject movement into the particular machine station.

The Sonoweld transducers, or frequency converters, are convertersspecifically manufactured for ultrasonic welding, and are manufacturedby the Sonobond Corporation, West Chester, Penna. The line spotfrequency converter consists of five independent frequency convertersrated at 2,000 watts, synchronized and balanced to furnish l0 kilowattsof power to the line spot ultrasonic welder. Two independent LCQO wattfrequency converters deliver the required power to the stake weldtransducer. A control console houses the timing devices for the twofrequency converter pulse intervals and relays that must be energized byattached equipment to initiate the weldmg processes.

Referring to FIG. 4, workpiece sensor A is comprised of photoelectricsensor 40 having beam 42, a relay 44 with nor mally open (N/O) points 46wired to one end of the coil of another relay 48, whose other coil endis wired to 8+. Relay 48 has N/O points 50, with the N10 point connectedto B+ and the operating point connected to one input of an AND-gate B.The other input of AND-gate B is wired to the first timing pulse(l70l85), which is generated when vane 1 passes in close proximity to amagnetically operated vane switch I0. The output of AND-gate B is usedas the prime input I to an 0N input unit 112 of memory unit C.

Memory unit C is an OFF-RETURN MEMORY of the type shown and described inGeneral Electric Publication BPC-BSSD, pages 2-l 5, entitledTransistorized Static Control, which uses four AND-NOT units to store abinary l signal. A standard output unit I14 of memory unit C has anoutput signal wired as the prime input II to the first stage of a shiftregister D. A B+ power "on reset is wired to one input of a NOT outputunit 118, and a reset from a second timing pulse (70-85) is wired to oneinput of an OFF input unit 1 16. The second timing pulse is generatedwhen vane 2 passes in close proximity to another vane operated switch10.

Shift register D is a series set-series add memory register having fourstages, in the preferred embodiment illustrated, but it can beappreciated that the number of stages employed is dependent upon therequirements of the apparatus being controlled. Each stage is a STEPMEMORY unit of the type shown on pages 2-66 through 2-69 of thepreviously referred to G. E. publication,. The details of shift registerD, in conjunction with manual control R will be subsequently explained.However, for our present description, each stage is a binary operatedflip-flop having prime and inhibit inputs, prime and inhibit outputsindicative of an "ON or an "OFF" state, respectively, with a step pulseand a reset pulse to set the flip-flop to the "ON" or "OI-F statedependent upon the state of the inputs. The second timing pulse (70-85)provides a stepping pulse for shift register D for every 360 of machineoperation. A power on reset from 11+ wired through N/O points whichclose after a short power "on" delay, sets each stage to the ofi' stateat the start of machine operation.

An output from stage 2 of shift register D is wired to an AC amplifierE, of the type shown on page 2-49 of the previously referred to G. E.publication, with an input 120 and terminals 122 and 124 connecting anAC power source to stake weld control G. The output of amplifier E,shown as 111, energizes a coil of a relay 126 in stake weld control G.Relay 126 closes its N/O points 130, when energized. The N/O points 130are wired in series with a third timing pulse (275290), indicated bylines X-X', and the coil of a relay 132, so as to initiate the operationof the stake weld transducer 134. A second output taken from the fourthstage of shift register D is wired through a like AC amplifier F toproduce output IV. Amplifier F has an input 140 and terminals 142 and144 connecting an AC power source across the coil of a relay 146 of linespot weld control H. Relay 146 has N/O points 150 connected in serieswith a fourth timing pulse (21 5230), indicated by lines Y-Y', and linesZZ' and a relay 152 so as to initiate the line spot weld transducer 154.The lines Z-Z' are wired across N/O relay points, as will be explainedsubsequently.

Body sensor .l is comprised of photosensor 100 with light beam 102,photoelectric relay 104 with M points 106 and time delay 108, aspreviously explained. The N/O points 106 of sensor 100 are adapted toconnect an AC power source across the coil ofa relay 110, having N/Opoints 111 and 113. 8+ is wired to the operating point of N/O points 111 and 113 and the MO point of points 111 is wired as an input to memoryunit I l. The NIC points 113 are wired to lines Z-Z', connected inseries control circuit of control H, as previously explained.

Memory unit K is an OFF-RETURN MEMORY similar to memory unit C. The NICpoint of points 111 is wired to ON input unit 160 of memory K. Thestandard output unit 162 has an output signal wired as input VI tocomparator M. First tim ing pulse (l70-l85) is wired into one input ofan OFF input unit 164 as a reset. The power "on unit reset (delayreset), through momentarily open contacts, puts 3+ on an input to NOToutput unit 166. A second reset, through switch S, puts on an input toOFF input unit 164, to reset memory unit K after power on" becausesensor 100 operates relay 110 momentarily on power "on" to triggermemory unit K on."

The output VI from memory unit K standard output unit 102 is wired toone input of an AND-gate 170 in comparator M. The second output from thefourth stage of shift register D is wired through time delay L and, asoutput V, is wired to the second input of AND-gate 170. Output V1 isalso connected to the input of a NOT-unit 174, and output V is alsoconnected to the input of a second NOT-unit 172. The output of NOT- unit174 is connected to an input of a second AND-gate 176 and the output ofNOT-unit 172 is connected to the second input of AND-gate 176. Theoutputs of AND-gates and 176 are commoned and connected as an input toamplifier N.

Amplifier N is identical to amplifiers E and F having an input 180, andterminals 182 and 104 connecting an AC power source across a coil of arelay 186 of motor control P. Relay 186 has N/O relay points 188 adaptedto connect an AC power source across drive motor 14.

In FIG. 5, shift register D and manual control R are illustrated.Illustrated in FIG. 5 is the series set-series add binary shift registerhaving four stages of STEP MEMORY flip-flops 200, as previouslyexplained. The prime input of each stage 200 is depicted by A, and theinhibit input of each stage 200 is depicted by B. Wired to the primeinput A of stage 1 is the output [I of standard output 1 14 of memoryunit C, and wired to the inhibit input of stage 1 is an inhibit outputof memory unit C taken from the NOT output unit 118 of memory unit C.

Each stage 200 also has a prime output D, designating a binary l whenthe stage is set on on," and III inhlbit output E, designating a binaryl when the stage is set off. The prime outputs D and the inhibit outputsE of stages 1, 2 and 3 are wired to the prime input A and the inhibitinput B of succeeding stages 2, 3 and 4, respectively. Prime output D ofstage 4 is wired as an input to amplifier F and also to time delay L.Prime output D of stage 2 is also connected to the input of amplifier E.A positive stepping pulse is wired to a step input C, of each stage.

In FIG. 5, provision is made for manual setting of the flipflops in eachstage 200 by providing auxiliary prime input A and auxiliary inhibit B.Manual control R consists of four, three position normally closed (N/C)double pole switches 202, having Add, Off," and "Subtract" positions.One pole of the Add" and Subtract" positions of the switches 202 arecommoned and wired to 8+. The second pole of each Add position of theswitches 202 is wired to auxiliary prime input A, whereas the secondpole of each Subtract" position of the switches 202 is wired toauxiliary inhibit input B. A positive delay reset is wired to resetinput C through N/O delay points that close after a short power on delaysetting each stage off.

In FIG. 6, a STEP MEMORY unit 200 with a steering network consisting ofprime input A, inhibit input B and step input C is shown, such asillustrated on page 2-68 of the previously designated G. E. publicationwith the designated inputs and outputs as detailed for FIG. 5. TwoPNP-transistors, 210 and 220, with associated circuitry that comprisesAND-NOT units (similar to those shown on page 2-6 of the aforementionedG. E. publication) are connected in a latch back arrangement so as toform the flip-flop portion of the STEP MEMORY unit.

Each transistor 210 and 220 has its respective emitter connecteddirectly to B+, and also to its respective base through biasingresistors 212 and 222, respectively. The respective bases of transistors210 and 220 are wired to B- through a plurality of paralleled seriesresistor combinations 213 and 214, and 223 and 224. The collector oftransistor 210 is wired as inhibit output (NOT output) E and also as alatch back to the junction of resistors 223 and 224 of the second seriescombination of resistors wired to the base of transistor 220. Thecollector of transistor 220 is wired as prime output (Standard Output) Dand also as a latch back to the junction of resistors 213 and 214 of thesecond series combination of resistors wired to the base of transistor210.

Prime input A is wired through the anode of a diode 216 to the junctionof resistors 213 and 214 of the first resistor series combination, resetinput C is wired to the junction of resistors 213 and 214 of the thirdresistor series combination, whereas auxiliary inhibit input B is wiredto the junction of resistors 213 and 214 of the fourth resistorcombination, all such combination of resistors having one end connectedto the base of transistor 210, and the other end connected to B.

Inhibit input B is connected through the anode of a diode 226 to thejunction of resistors 223 and 224 of the first resistor seriescombination, and auxiliary prime input A is wired to the junction ofresistors 223 and 224 of the third resistor series combination, all suchcombinations of resistors having one end connected to the base oftransistor 220.

Step timing pulse C is connected to the anodes of diodes 216 and 226through two charging capacitors 218 and 228, respectively.

In P10. 7, a cut away view of the body sensor .1 of FIG. 1 is shown inits preferred embodiment. A clamping block surrounding body piece 39,has a round horizontal access bore 252 running from the outer surface ofblock 250 to the inner curved surface where the block 250 surrounds theouter curved surface of body piece 39. A round elongated rod 254 isinserted in bore 252 and supported by bushings 256. Photosensor 100 ismounted so that the center line 103 of light beam 102 of photosensor 100and centerline of elongated rod 254 are coincident. This centerline 103and a diameter of body piece 39 coincide at some point A on the outersurface of body piece 39. Radii drawn from point A and from a lowerperpendicular diameter point, point B, define an angle 262, designatedby a. An inner tip 255 of rod 254 is cut off at an angle correspondingto angle 262, and rod 254 is adjusted longitudinally within bore 252 topermit photosensor 100 to sense the reflected beam from body piece 39.Thus, bore 252 may be cut in block 250 in any horizontal position, online with body piece 39, within block 250, and inner tip 255 of rod 254is then cut OR at angle 262, corresponding to the resultant anglecreated by the radii under discussion.

OPERATION in FIG. 2, showing a representation of a typical machineemploying the control apparatus of this invention, motor 14, whenenergized, drives shaft 12, and timing vanes 1-4 and vertical bevel gear16, all of which are fixedly attached to shaft 12. A second bevel gear16 causes shaft 18 to rotate, which, in turn, rotates drive cam 20. Asdrive cam 20 rotates, feed bar crank 24 is driven in an oscillatorymotion by pivot pin 22. The feed bar crank 24 transfers this oscillatorymovement to feed bar 28 by means of a second pivot pin 26. Timing vanes1-4, of magnetic material, are attached to shaft 12 in a predeterminedmanner, as illustrated by FIG. 3, so as to have a timed relationshipwith the oscillatory movement of feed bar 28. As is shown by FIG. 2,magnetic timing vane 1 is attached to shaft 12 to cause deflection ofthe operating vane of a limit switch so as to transfer the N/O pointsof'switch 10 when the feed bar 28 has reached its maximum oscillatorymovemerit to the right. Limit switch 10 is representative of amagnetically operated reed switch of any well-known type that closes N/Opoints when a vane having magnetic properties pass inclose proximity tothe switch points.

Referring again to FIG. 2, workpieces 32 are fed from a feed hopper tofeed bar 28, when feed bar 28 is in its left most oscillatory position.Typical of transport units employed for such machines are feed fingers34 biased upward with compression springs 36 and which are designed tofeed the workpieces 32 to the right when feed bar 28 is oscillated tothe right, and then to depress so as to ride under the workpieces 32(held in place by clamping means not shown, but which is well known inthe art) as feed bar 28 is driven to the left. As workpieces 32 are fedto the right through the various machine stations, workpiece sensor 40senses a workpiece 32 by means of a photobeam 42 at a station which canbe considered an input station. This sensing of a workpiece 32 activatesa memory, as will be detailed subsequently. Two cycles later theworkpiece 32 has been transported to station 60 where it has been formedinto body piece 39 around a horn 38, by a process well known in the art.This station 60 is designated as a form and stake weld station, for thebody piece 39 is formed here and then work is performed in the nature ofa stake weld by ultrasonic welders. Two cycles later, the staked bodypiece 39 should have been transported to an output station 80, known, asa line weld station, where work in the nature of ultrasonic line weldingis done if the body piece 39 has been transported to station 80. If thestake body piece 39 should be defectively welded in the stake weldstation, the staked body piece 39 may not be transported to station 80.Body sensor in body photo scanner J is used to detect body piece 39movement into station 80, and also body piece 39 movement out of station80, as was previously explained.

Thus, it is seen in FIG. 2, that timing pulses 1-4', workpiece 32sensing, and body piece 39 movement are all achieved in timedrelationship to the machine under control, and that drive power to motor14 can be interrupted or controlled as desired.

FIG. 1 illustrates in block diagram form the preferred embodiment ofthis invention, whereas F IG. 4 is a schematic illustration of thisinvention. As a result, the detailed operation of this invention will bedirected to FIG. 4.

As workpiece 32 is transported to the input station, at A, by feed bar28, it is sensed by beam 42 of workpiece sensor 40, and relay 44 willbecome energized, closing N/O points 46 within sensor 40. When N/Opoints 46 close, relay 48 becomes energized to close N/O points 50 so asto put a binary 1" signal on an input of AND-gate B. Drive shaft 12rotates magnetic vanes 1 through 4 in timed relationship to feed bar 28,as previously explained, so, as vane 1 passes in close proximity to itslimit switch 10, the reed switch normally open points close and a binaryl signal is put on the second input of AND gate B.

As is well known, an AND-gate is a circuit which has at least two inputsand one output. If both inputs are a binary l the output will also be abinary "1." Under all other conditions, the output will be a binaryConsequently, with a binary 1" on both inputs of AND gate 13, there is abinary l as output 1, serving as an input to ON input unit 112 of memoryunit C. As previously stated, memory unit C is in the form of anOFF-RETURN MEMORY, wherein a binary l to the ON input unit 112 producesa binary l output from unit 114. This OFF-RETURN MEMORY is of the typedepicted on pages 2-15 of the aforementioned G. E. publication, whereinfour AND-NOT units are wired in latch back fashion to constitute amemory unit. As soon as power is applied, units 112 and 116 produce abinary "l output immediately, but the delay reset delays its output longenough to insure that output 118 turns "on." With units 112 and 116 bothdriving unit 118 with binary l signals, unit 114 cannot turn on, so thestandard output from unit 114 is left in the binary 0" condition. When abi nary 1" input is fed into unit 112, unit 112 loses its binary "1output, causing unit 114 to turn on and feed a binary l to a third inputof unit 118, causing unit 118 to lose its binary 1 output. The loss ofthis binary l output from unit 118 removes the other binary l input tounit 114, insuring an output from unit 114 of a binary l regardless ofthe condition of unit 112, even if unit 112 should again have an outputof a binary l by releasing the binary "1 input to it. The OFF-RETURNMEMORY can be turned off with a binary 1 input to OFF unit 116,resulting in turning on unit 118, giving a binary 1 output from unit 118which in turn, turns ofi'" unit 114. Thus, the first binary 1" input,whether it is into ON unit 112 or into OFF unit 116, will takeprecedence as long as it is in the binary l state. For example, thebinary "1 input into ON unit 112 removes the binary 1" output from ONunit 112 which in turn removes an input of a binary "1 to OFF unit 116.Once this binary l input to OFF unit 116 is removed, actuating thesecond timing pulse so as to produce a binary "1" input to OFF unit 116,has no effect. The first binary 1 input signal to the OFF-RETURN MEMORYlocks out the effect of the second binary l input while the first binaryl input is being maintained.

The binary 1" output from unit 114, output 11, primes the first stage ofshift register D, which is comprised of four bistable STEP MEMORY units200, as previously described. These STEP MEMORY units 200 may take theform as shown on page 2-68 of the aforementioned G. E. publication,wherein a steering network is used in conjunction with a flip-flopcomposed of two AND-NOT units. Each STEP MEMORY unit 200 comprises onestage of the shift register D, and includes two PNP-transistors stages,as shown in FIG. 6, one transistor conducting while the other transistoris cut off. One condition of each unit is the normally on" or binary lcondition and the remaining condition being called the off condition, orthe binary condition.

Referring now to FIGS. and 6, each stage of the binary shift register Dis normally reset off with the 13+ delay reset into the reset input C,causing transistor 210 to conduct, to produce a binary 1" condition atthe NOT output E, and producing a binary 0" condition at the regularoutput D. With reference to both FIGS. 5 and 6, priming stage 1transistor 210 with a binary l input into prime input A and a binary 0"input into inhibit input B, conditions the base of transistor 210 toturn the flip-flop within STEP MEMORY unit 200 on by conditioning thebase of transistor 210 to cut transistor 210 "off," and also conditionsthe base of transistor 220 through diode 226 to permit conduction intransistor 220 as transistor 210 conduction is cut off. With theflip-flop of a memory unit 200 in this primed condition, a positivepulse into the step input C will put a strong momentary positive pulseonto the base of conducting transistor 210 through capacitor 218 anddiode 216, driving the base strongly positive, reducing conductionthrough transistor 210, and causing the collector output to decrease.This decrease in the collector output of transistor 210 will bereflected to the base of transistor 220 through resistor 223 of thesecond series of resistor combinations to initiate conduction intransistor 230. As transistor 220 begins to conduct, the output from thecollector of transistor 220 at the junction of the second series ofresistors 213 and 214 will go more positive, placing a positive bias onthe base of transistor 210. Through this regenerative action, transistor210 is cut "off" and transistor 220 is driven into saturation, and theflip-flop within the memory unit 200 is changed from the "off" state tothe on state or from the binary 0" state to the binary l state. Theopposite condition of the flip-flop can be achieved by placing aninhibiting condition on input A (binary 0) and a priming condition oninput 13 (binary "1") when the positive timing pulse is impressed onstep input C.

The desired state of each step memory unit 200 can be manually achievedwith auxiliary prime input A and auxiliary inhibit B and the manualcontrol R, by manually operative switches 202 removing a binary 1"signal from the particular terminal involved. For an ADD operation in aparticular stage, it is only necessary to manually operate switch 202for the STEP MEMORY unit 200 involved, so as to remove the 8+ to the Aterminal (this puts a negative on the base of transistor 220) to causeconduction in transistor 220 and thus produce a binary l output atoutput D, signifying an on" condition for the flip-flop within the STEPMEMORY unit 200 that is being set. In the same manner, a STEP MEMORYunit 200 can be reset off for a SUBTRACT operation, by operating aswitch 202 so that the B+ into the auxiliary input B terminal isremoved, causing the base of transistor 210 to go negative to drivetransistor 210 into conduction, thus producing a binary 1" signal at NOToutput E. Thus, the flip-flop within the STEP MEMORY unit 200 can be setto the desired state through the loss of a binary 1" signal to theparticular terminal that is connected with the base of the transistorwhich it is desired to cause to conduct, and thus, to produce the binaryl output therefrom.

Therefore, priming the input to stage 1 with a binary 1" prime input 11into prime input A and an inhibit input into input B, will conditionstage 1 to change from its power on" reset binary 0" state to a binary1" state when a positive timing pulse is impressed upon step input C.Turning the first state "on" will prime the second stage, and when thenext positive timing pulse is impressed on the commoned step input C,the second stage will be changed from its normally power on reset binary0" state to a binary l state. This process will continue, regardless ofhow many stages are employed,

with each preceding stage priming each succeeding state. Also, it willbe appreciated that stage 1 can be primed continuously for every machinecycle, and thus permit shill register D to be set in timed relationshipwith each workpiece 32 that is fed into the machine input station, at A.

Referring again to FIG. 4, as stage 2 of shift register D is turned"on," a binary l output is fed to an input of amplifier E, which is aone ampere output amplifier, controlling AC power to a particular load.Such an amplifier can take the form of the AC output amplifier as shownon page 2-49 of the aforementioned G. E. publication. The terminals 122and 124 permit the AC power source to be connected across the coil ofrelay 126 in the fonn of output [I]. Energizing the coil of relay 126closes normally open contact points 130, and when third timing pulse(275-290) occurs, a series circuit is completed through lines X-X' andthe coil of relay 132. Energizing the coil of relay 132 will initiatethe self-contained timing controls, as previously explained,incorporated in the ultrasonic welding equipment 134. The timing controlof welding equipment 134 thereafter control the timed operation of thewelding process for stake welding the body piece 39.

As the body piece 39 is transported by feed bar 28 through the machineunder control, the memory unit C is reset for each machine cycle bysecond timing pulse (70-85), and set by first timing pulse (170-185) foreach workpiece 32 sensed by sensor 40 as each workpiece 32 is fed intothe machine under control. Second timing pulse (7085) also steps theshift register D in timed relationship with each workpiece 32 beingtransported through the machine.

As a particular body piece reaches the output station 80, shift registerD should have a binary l on the output of stage 4 to correspond to theposition of body piece 39 at output station 80. Body sensor 100 throughbeam 102 senses a body piece 39 as it is moved into output station 80.Beam 102, sensing a body piece 39, energizes the coil of relay I04,closing normally open points 106 within sensor 100. Closing normallyopen points 106, connects an AC power source across the coil of relay110, energizing the coil to close two normally open contacts 1 11 and113. The closing of normally open contacts 111 feeds 13+, or a binary1," to ON input 160 of memory unit K. Memory unit K is an OFF-RETURNMEMORY similar to memory unit C. Putting a binary "l" on input 160causes a binary l output from unit 162, and as the unit is latched backthrough appropriate wiring, as previously explained, the binary l outputfrom unit 162 appears as output Vl into AND-unit 170 of comparator M.

Closing the normally open points 113, places the B+, by means of wiringZ-Z' in the controlled circuit of line spot control H. As previouslystated, the fourth stage of shift register D should have a binary loutput at this time. The binary 1" output from the fourth stage of shiftregister D biases input causing an output from amplifier F in the formof 1V causing an AC power source to be impressed across the coil ofrelay 146 by means of terminals 142 and 144. Energizing the coil ofrelay 146 causes normally open point 150 to close, completing a circuitacross Z-Z' (N10) points 113) and Y-Y', when fourth timing pulse(2l5-230) appears across Y-(' to energize the coil of relay 152 so as toinitiate the timing mechanism within line spot control H weldingapparatus 154. Therefore, it should be apparent that welding apparatus154 will not be energized should a body piece 39 not be sensed by sensor100 moving into station 80 when the fourth stage of shift register I)has a binary 1" output. Also, should body piece 39 not be transportedout of welding station 80, no welding will be permitted on the nextmachine cycle by welding apparatus 154, because the time delay 10!!incorporated within sensor 100 will cause the coil of relay 104 todeenergize after a predetermined time, and thus cause normally openrelay points 113 to open, and remain open, and thus interrupt thecontrol circuit within line spot control H.

The comparator M compares the output signal from the last stage of shiftregister D with the setting of memory unit K, to insure that the shiftregister D stepping and the workpiece 32 and body piece 39transportation coincide. Should the output signals not compare in pointof time, the machine under control is stopped.

Again, referring to FIG. 4, a binary "1" input to ON input unit 160 ofmemory K causes a binary l to be stored and a binary l appears as outputVl at the output unit 162. A binary "1" from the fourth stage of shiftregister D through a time delay unit I. having an adjustable setting ofpoint 0.1 to 2 seconds, appear as output V. This time delay unit L isnecessary because the binary l output from stage 4 of shift register Dappears earlier in the machine cycle than the binary 1" output frommemory K and it is desired to compare the two output signals at onetime. The machine under control normally operates at an operating speednecessary to transport five workpieces per second through the machine,so delay unit L is made adjustable within the range specified and alsoto provide for any loss of operating speed.

Binary l outputs V and VI are impressed upon AND-unit 170, producing abinary l output therefrom that is used as an input to output amplifierN. A binary l input into 180 of amplifier N produces an output Vllacross terminals 182 and 184 to energize the coil of relay 186.Energizing the coil of relay I86 closes the N points 188, placing anenergizing AC power source across motor 14. Should either output V or V]not be a binary l when compared, no energizing output will appear fromAND-unit 170, and the motor control circuit P will be deenergized andmotor 14 will stop.

Provision is made in comparator M for the machine to be in the "run modewhen no material is being transported through the machine or has not yetbeen fed up to the output station under normal conditions. Both outputsV and VI should be in a binary 0" state at this time. The binary 0" ofoutputs V and VI are impressed upon NOT-units 172 and 174, respectively.The output signals from the NOT-units, under this condition, will bothbe a binary l," inverting the binary 0" inputs. These binary 1" signalsare impressed upon the two inputs of AND 176 so as to produce a binary 1input signal into output amplifier N, and thus energize the motorcontrol circuit P as before, Thus, it is seen that motor control P willremain energized as long as a binary l input signal is present at theinput to output amplifier N.

The reset to memory unit K has two forms. The manual reset from switch Sputting a 8+ on an input into the OFF unit 164, is necessary after poweron," because body sensor 100 is triggered on on power on," which in turntriggers memory K on. Therefore, memory unit K must then be reset "off"to permit normal operation. For operation after the manual reset, firsttiming pulse (l70l85), putting a 8+ on an input into OFF unit 164 ofmemory unit K, will reset the memory unit only in the event body sensor100 is not sensing a body piece 39 moving into output station 80. Thisis because the first binary l input into memory unit K takes precedenceas long as such binary 1" input is available, as was explained for theoperation of the similar memory unit C,

Referring now to FIG. 7, the body sensor apparatus .l is shown in acutaway view. In the preferred embodiment shown, means had to be devisedto sense body piece 39 within the solid clamping blocks necessitated bythe ultrasonic welding process. The design of the machine under controldid not permil sensing by means of a lever, nor by a sensing unit with abeam having a centerline on line with a diameter of body piece 39 withinthe block.

In the left hand clamp block 250 at line weld station 80, a roundhorizontal bore 252 is cut into block 252 from its outer surface to theinner curved surface surrounding body piece 39. An elongated plexiglassrod 254, having the property of directing light rays from one polishedsurface through the rod to a second polished surface, is inserted withinbore 252 and retained within bore 252 by bushings 256. Body sensor 100is mounted so that the centerline 103 of light beam [02 is coincidentwith the centerline of the elongated plexlglass rod 254.

The optics of the sensor 100 employed in the control apparatus of thisinvention permits only a 7 deviation of reflected light from thecenterline of the return beam of the sensor to energize relay 104 withinthe sensor. Therefore, the construction of the apparatus under controlrequired that the tip 255 of rod 254 be cut at a particular angle 262,defined as a. This angle a is derived by defining point A on the outersurface of body piece 39. This is defined by the intersection of thecenterline 103 of light beam 102 and the outer surface of body piece 39.A radius drawn from point A to the center of body piece 39, and a secondradius drawn perpendicularly therefrom to a point B on the lower outersurface of body piece 39 define this angle a. Thus, bore 252 may be cutat any horizontal position in block 250, on line with body piece 39, todefine the angle a. Cutting tip 255 of rod 254 at angle 262, defined asa, and adjusting rod 254 longitudinally within bore 252, brings thereturn path of beam 102 of sensor within the the control limits ofsensor 100 to sense a body piece 39 within the clamping block 250. Theborn 38 (see FIG. 2) around which body piece 39 is formed, has adarkened spot on it on line with bore 252 and rod 254 to preventerroneous reflected signals to be sensed by sensor 100 when no bodypiece 39 is present at this station of the machine.

Having thus described the preferred embodiment of the control apparatus,it will be obvious to one skilled in the art that various modificationsmay be made without departing from the invention as hereinafter definedin the claims.

I claim: 1. An apparatus controlling an automatically fed machine, saidmachine having a work-performing means and operating cycles and at leastan input and an output station wherein workpieces are transported alonga conveyance path so as to be fed into the input and the outputstations, the combination comprising:

pulse generator means for generating a plurality of machine timingpulses, said pulse generator being operatively connected to said machinein timed relationship therewith;

first means for detecting the presence of each said workpiece at saidinput station and having a means for producing a signal when detectingthe presence thereof, said first detecting means also having means forstoring a memory of said workpiece presence signal in coincidence withthe input thereto of one of said timing pulses, said memory meansproducing an output signal when such presence signal has been storedtherein;

means fore registering the presence of each said workpiece in saidmachine upon a coincidence of the input into said register means of theoutput signal from said memory means and one of said timing pulses, saidregister means producing at least an output signal and havingenergizable means being energized by said output signal for controllingsaid work performing means so as to perform work on each said workpiecein the event each said workpiece is being transported through saidmachine;

second means for detecting the feeding of each said workpiece into saidoutput station and having mans for producing a signal when detectingsaid feeding, said second detecting means also having means for storinga memory of said feeding signal, said second detecting memory meansproducing an output signal when said feeding signal has been storedtherein; and

comparator means for producing at least a control signal on thecoincident input thereto of an output signal from said register meansand from said second detector memory means, a said control signalenergizing machine control means so as to permit the machine to continueto transport said workpieces along the conveyance path.

2. An apparatus as set forth in claim 1, wherein:

said generator means produces a first, second, third and fourth pulsefor each operating cycle, said pulses having variable machine timings;

said first detection means including a first sensor in close proximityto said input station and producing said workpiece presence signal, saidmemory means having a signal detection means for producing an outputsignal upon the coincidence of the input thereto of said output fromsaid first sensor and said first timing pulse and having a first memorystoring said output signal from said signal detection means so as toproduce an output signal when storing said output signal from saidsignal detection means therein;

said register means includes at least a first and last bistableflip-flop, each said flip-flop being interconnected with another saidflip-flop and each having an off and an on state, said coincidence ofsaid input signals into said register means serving to turn on saidfirst bistable flip-flop, and

said second detector means having a sensor in close proximity with saidoutput station and producing an output signal only when detecting thefeeding of a workpiece into said output station, said second detectormemory means storing said feeding signal produced by said sensor so asto produce an output signal when said feeding signal has been storedtherein.

3. An apparatus as set forth in claim I, wherein said comparator meansincludes a differential amplifier for comparing an output signal fromsaid register means with said output from said second detector memorymeans, said differential amplifier emitting a control signal energizingsaid machine control means in the event the two said outputs occur atthe same point in time.

4. An apparatus as defined in claim 3, wherein said differentialamplifier comprises a first and second logic AND- gate and a first andsecond NOT-unit, means for applying an output signal from register meansto said first AND-gate and to said second NOT-unit to produce aninverted signal from said second NOT-unit, means for applying the outputsignal from said second detector memory means to said first AND- gateand to said first NOT-unit so as to produce an inverted signal from saidfirst NOT-unit, means for applying said inverted output signals fromsaid first and second NOT-units as input signals to said second AND-gateto produce a second control signal from said comparator on a coincidenceof said inverted output signals, said second control signal energizingsaid machine control means when said machine is in an idle conditionwherein no workpieces should have been fed into said output station.

5. An apparatus as defined in claim 4, wherein the signal detectionmeans is a third AND-gate having means for applying a binary l signal toan input of said first memory means.

6. An apparatus as set forth in claim 5, wherein said first memory meansincludes a bistable memory unit storing said output signal from saidsignal detection means.

7. The apparatus as defined in claim 6, wherein said register means hasa plurality of bistable flip-flops including said last and the firstflip-flop, means connecting the output leads of a preceding flip-flop tothe input leads of a succeeding flip-flop. respectively, thereby topermit setting any flip-flop at any one time, said flip-flops developinga prime and inhibit binary l output signal on their output leadsaccording to the set or reset state of said flip-flop, said secondtiming pulse setting any flipflop wherein the preceding flip-flop has aprime signal on one of its output leads and resetting any flip-flopwherein the preceding flip-flop has an inhibit signal on said outputlead; and means for applying the prime output signal of said lastflip-flop to said first AND-gate and said second NOT-unit.

8. An apparatus controlling an automatically fed machine, said machinehaving a work-performing means and operating cycles and at least aninput and an output station wherein workpieces are transported along aconveyance path so as to be fed into the input and the output stations,the combination comprising:

pulse generator means for generating a plurality of machine timingpulses, said pulse generator being operatively connected to said machinein timed relationship therewith; first means for detecting the presenceof each said workpiece at said input station, said first detecting meansproducing an output signal when such presence has been detected incolncldence with the Input thereto of one of said timing pulses;

means for registering the presence of each said workpiece in saidmachine upon a coincidence of the input into said register means of theoutput signal from said first detecting means and one of said timingpulses, said register means producing at least an output signal forcontrolling said work performing means so as to perform work on eachsaid workpiece in the event each said workpiece is being transportedthrough said machine;

second means for detecting the feeding of each said workpiece into saidoutput station and having means for producing a signal when detectingsaid feeding, said second detecting signal means producing an outputsignal when said feeding has been detected; and

comparator means for producing at least a control signal on thecoincident input thereto of an output signal from said register meansand from said second detecting signal means, a said control signalenergizing machine control means so as to permit the machine to continueto transport said workpieces along the conveyance path.

1. An apparatus controlling an automatically fed machine, said machinehaving a work-performing means and operating cycles and at least aninput and an output station wherein workpieces are transported along aconveyance path so as to be fed into the input and the output stations,the combination comprising: pulse generator means for generating aplurality of machine timing pulses, said pulse generator beingoperatively connected to said machine in timed relationship therewith;first means for detecting the presence of each said workpiece at saidinput station and having a means for producing a signal when detectingthe presence thereof, said first detecting means also having means forstoring a memory of said workpiece presence signal in coincidence withthe input thereto of one of said timing pulses, said memory meansproducing an output signal when such presence signal has been storedtherein; means fore registering the presence of each said workpiece insaid machine upon a coincidence of the input into said register means ofthe output signal from said memory means and one of said timing pulses,said register means producing at least an output signal and havingenergizable means being energized by said output signal for controllingsaid work performing means so as to perform work on each said workpiecein the event each said workpiece is being transported through saidmachine; second means for detecting the feeding of each said workpieceinto said output station and having mans for producing a signal whendetecting said feeding, said second detecting means also having meansfor storing a memory of said feeding signal, said second detectingmemory means producing an output signal when said feeding signal hasbeen stored therein; and comparator means for producing at least acontrol signal on the coincident input thereto of an output signal fromsaid register means and from said second detector memory means, a saidcontrol signal energizing machine control means so as to permit themachine to continue to transport said workpieces along the conveyancepath.
 2. An apparatus as set forth in claim 1, wherein: said generatormeans produces a first, second, third and fourth pulse for eachoperating cycle, said pulses having variable machine timings; said firstdetection means including a first sensor in close proximity to saidinput station and producing said workpiece presence signal, said memorymeans having a signal detection means for producing an output signalupon the coincidence of the input thereto of said output from said firstsensor and said first timing pulse and having a first memory storingsaid output signal from said signal detection means so as to produce anoutput signal when storing said output signal from said signal detectionmeans therein; Said register means includes at least a first and lastbistable flip-flop, each said flip-flop being interconnected withanother said flip-flop and each having an off and an on state, saidcoincidence of said input signals into said register means serving toturn on said first bistable flip-flop; and said second detector meanshaving a sensor in close proximity with said output station andproducing an output signal only when detecting the feeding of aworkpiece into said output station, said second detector memory meansstoring said feeding signal produced by said sensor so as to produce anoutput signal when said feeding signal has been stored therein.
 3. Anapparatus as set forth in claim 1, wherein said comparator meansincludes a differential amplifier for comparing an output signal fromsaid register means with said output from said second detector memorymeans, said differential amplifier emitting a control signal energizingsaid machine control means in the event the two said outputs occur atthe same point in time.
 4. An apparatus as defined in claim 3, whereinsaid differential amplifier comprises a first and second logic AND-gateand a first and second NOT-unit, means for applying an output signalfrom register means to said first AND-gate and to said second NOT-unitto produce an inverted signal from said second NOT-unit, means forapplying the output signal from said second detector memory means tosaid first AND-gate and to said first NOT-unit so as to produce aninverted signal from said first NOT-unit, means for applying saidinverted output signals from said first and second NOT-units as inputsignals to said second AND-gate to produce a second control signal fromsaid comparator on a coincidence of said inverted output signals, saidsecond control signal energizing said machine control means when saidmachine is in an idle condition wherein no workpieces should have beenfed into said output station.
 5. An apparatus as defined in claim 4,wherein the signal detection means is a third AND-gate having means forapplying a binary ''''1'''' signal to an input of said first memorymeans.
 6. An apparatus as set forth in claim 5, wherein said firstmemory means includes a bistable memory unit storing said output signalfrom said signal detection means.
 7. The apparatus as defined in claim6, wherein said register means has a plurality of bistable flip-flopsincluding said last and the first flip-flop, means connecting the outputleads of a preceding flip-flop to the input leads of a succeedingflip-flop, respectively, thereby to permit setting any flip-flop at anyone time, said flip-flops developing a prime and inhibit binary''''1'''' output signal on their output leads according to the set orreset state of said flip-flop, said second timing pulse setting anyflip-flop wherein the preceding flip-flop has a prime signal on one ofits output leads and resetting any flip-flop wherein the precedingflip-flop has an inhibit signal on said output lead; and means forapplying the prime output signal of said last flip-flop to said firstAND-gate and said second NOT-unit.
 8. An apparatus controlling anautomatically fed machine, said machine having a work-performing meansand operating cycles and at least an input and an output station whereinworkpieces are transported along a conveyance path so as to be fed intothe input and the output stations, the combination comprising: pulsegenerator means for generating a plurality of machine timing pulses,said pulse generator being operatively connected to said machine intimed relationship therewith; first means for detecting the presence ofeach said workpiece at said input station, said first detecting meansproducing an output signal when such presence has been detected incoincidence with the input thereto of one of said timing pulses; meansfor registering the presence of each said workpiece in said machine upona coincIdence of the input into said register means of the output signalfrom said first detecting means and one of said timing pulses, saidregister means producing at least an output signal for controlling saidwork performing means so as to perform work on each said workpiece inthe event each said workpiece is being transported through said machine;second means for detecting the feeding of each said workpiece into saidoutput station and having means for producing a signal when detectingsaid feeding, said second detecting signal means producing an outputsignal when said feeding has been detected; and comparator means forproducing at least a control signal on the coincident input thereto ofan output signal from said register means and from said second detectingsignal means, a said control signal energizing machine control means soas to permit the machine to continue to transport said workpieces alongthe conveyance path.